Magnetic disk drives, as an example of a rotating disk type storage device, are used as data recording devices for personal computers, servers, and so on. The magnetic disk drives are each provided with a discoid magnetic disk having a recording surface formed by providing a magnetic layer on a substrate and provided so as to rotate around a spindle shaft, a head stack assembly, and a control unit for controlling data read/write to the magnetic disk and operation of the head stack assembly.
The head stack assembly is composed of head gimbal assemblies each corresponding to respective one of recording surfaces of the magnetic disk(s), a carriage, and a pivot cartridge, each of the head gimbal assemblies being fixed to an actuator arm provided to the carriage. The head gimbal assembly is equipped with a slider provided with a magnetic head for reading and writing data with the magnetic disk and for providing an air bearing surface (ABS). A part of the carriage is provided with a coil support, and the coil support holds a voice coil. The voice coil is disposed in the magnetic field formed by a voice coil magnet and a voice coil yoke, and the voice coil magnet, the voice coil yoke, and the voice coil form a voice coil motor (VCM) generating a driving force for rotating the carriage. The pivot cartridge is fitted in an opening provided to the carriage, and it is arranged so that the head gimbal assembly is allowed to rotate around the pivot shaft, the shaft of the pivot cartridge.
When the magnetic disk rotates, the airflow on the surface forms the air bearing, and provides ascending force to the air bearing surface of the slider, thereby lifting the slider slightly from the surface of the magnetic disk. By the driving force of the voice coil motor, the slider rotates around the pivot shaft in substantially the radial direction of the magnetic disk while slightly lifted from the surface of the magnetic disk, thus the magnetic head can read and write data at a predetermined position on the surface of the disk.
In accordance with the density growth in magnetic recording to the magnetic disk, improvement in positioning accuracy of the magnetic head is required to such magnetic disk drives. However, the actuator arm and the head gimbal assembly both moving on the surface of the magnetic disk are swung by the airflow in the rotational direction caused by the rotation of the magnetic disk. If the actuator arm or the head gimbal assembly is swung, a so-called windage vibration, which is the vibration of the magnetic head caused by the swing of the actuator arm or the head gimbal assembly transmitted thereto, is increased. The windage vibration becomes one of the factors degrading the positioning accuracy of the magnetic head, and accordingly, needs to be reduced. There has been proposed a magnetic disk drive (see, for example, Japanese Patent Publication No. 2004-234784 (“Patent Document 1”), Japanese Patent Publication No. 2002-313061 (“Patent Document 2”), and Japanese Patent Publication No. 2002-184154 (“Patent Document 3”)) provided with a spoiler disposed on the upstream side of the head stack assembly in the airflow in the rotational direction caused by the rotation of the magnetic disk in order for reducing the windage vibration of the magnetic head. This spoiler is capable of weakening the airflow towards the actuator arm or the head gimbal assembly to reduce the windage vibration of the magnetic head. It should be noted that in the present specification, the term “upstream side” and “downstream side” are assumed to be used to indicate directional positions of the airflow in the rotational direction caused by the rotation of the magnetic disk with respect to the objective component.
However, since the wing of the spoiler is disposed in the airflow of the magnetic disk rotating at high speed in such a magnetic disk drive, the pressure in the downstream side of the wing is lowered to cause negative pressure. If the negative pressure is caused in the airflow, there is caused in the negative pressure portion a flow of air flowing in on the surface of the magnetic disk from the surrounding area of the outer periphery of the magnetic disk towards the spindle shaft. Since the head stack assembly and other components exist in the surrounding area of the outer periphery of the magnetic disk, there are relatively large amounts of suspended dust and attached dust. Therefore, it is conceivable that these kinds of dust are caught up in the flow of air from the surrounding area of the outer periphery of the magnetic disk towards the spindle shaft and are attached to the surface of the magnetic disk. If the magnetic head passes above the surface of the magnetic disk attached with the dust, the dust is pinched between the magnetic head and the magnetic disk to cause disadvantages of damaging the magnetic disk to loose the recorded data and damaging the magnetic head.
There is proposed a technology for preventing such dust caused inside the device from obtaining entrance on the surface of the magnetic disk (see, for example, Japanese Patent Publication No. 6-111560 (“Patent Document 4”) and Japanese Patent Publication No. 2006-18937 (“Patent Document 5”)). The rotating disk type storage device disclosed in Patent Document 4 prevents that the negative pressure is caused on the downstream side of the arm and the air containing the dust flows backward through a through hole of the arm to enter a disk pack housing by providing flow-blocking means to the through hole to form an area with higher pressure than that in the surrounding area of the flow-blocking means. It should be noted that since the arm has a configuration for linearly moving towards the rotational center of the magnetic disk, the distance between the arm and the flow-blocking means can always be kept constant, thus the pressure in the high pressure area can be stabilized, thereby reliably preventing the air containing the dust from flowing backward. However, in the case in which the magnetic head is moved on the magnetic disk by rotationally moving the arm, the distance between the arm and the flow-blocking means cannot always be kept constant, and accordingly, the pressure in the high pressure area might be changed to cause the air containing the dust to flow backward. Further, there is a disadvantage that the arm is swung by the airflow in the rotational direction caused by the rotation of the magnetic disk to increase the windage vibration of the recording head.
Further, in a magnetic disk drive disclosed in Patent Document 5, the dust is removed by providing an airflow path to a spindle hub and disposing a filter in the middle of the airflow path, or by attaching an electrostatic filter to a shroud. However, since the negative pressure is caused on the downstream side of a guide arm when the magnetic head is moved on the magnetic disk, the air containing the dust might flow in from the outside of the magnetic disk on the magnetic disk and might be attached thereto. Further, there is a disadvantage that the guide arm is swung by the airflow in the rotational direction caused by the rotation of the magnetic disk to increase the windage vibration of the magnetic head.